We have yet to fully define the immune responses associated with immunologic control of HIV replication. To develop an effective vaccine, we need to better understand the responses that may be controlling HIV, and why these defenses might fail. This study examines the T cell immune responses to HIV in naturally-infected subjects. It compares these responses with those generated against other viruses and non-viral pathogens in order to determine mechanisms of success or failure of an immune response.We have yet to fully define the immune responses associated with immunologic control of HIV replication. To develop an effective vaccine, we need to better understand the responses that may be controlling HIV, and why these defenses might fail. This study examines the T cell immune responses to HIV in naturally-infected subjects. It compares these responses with those generated against other viruses and non-viral pathogens in order to determine mechanisms of success or failure of an immune response.